Sunday Science: Smaller tubing increases sap yield - WCAX

In this position, he's spent a lot of time with maple producers and observed a few things.

"The smaller producers, the ones that generally don't use pumps, their production is usually not very good," he says.

He attributes this to the lack of a strong vacuum forming within the tubing network.

"Without vacuum you're entirely dependent on the pressure that's created in the tree when we have freezing and thawing," he says.

Wilmot says that this pressure, and hence the dripping, stops after a few days above freezing. So a vacuum is needed to keep the sap flowing. A weaker vacuum is traditionally accomplished with gravity tubing down a slope.

"Gravity makes this work because the sap builds up in the tubing and the weight of the sap allows a vacuum to be created," he says.

Wilmot observed that this type of vacuum doesn't work all that well; he hypothesized that the standard 5/16" of an inch diameter tubing was too large.

"This is the 3/16" interior diameter and that's the tubing I've been developing a use for," he says.

This smaller tubing has about one third the interior volume of the standard tubing-- This means the same amount of sap extends about 3 times as far in a smaller tube versus a standard tube. Wilmot says this means in theory, the vacuum effect is three times as strong.

"The results have been very, very pleasing, very satisfying for me," Wilmot says.

We gave it a try indoors. The pressure gauge started at zero, but once lifted, a solid vacuum formed.

"We've created five inches of vacuum just by suspending," he says.

Initially maple manufacturing companies weren't making 3/16" diameter tubing, so producers had to look to hardware stores. But thanks to Wilmot's research that's not the case anymore.

"Some of the big maple manufacturing companies heard about people that were using this, and said we want to get in on this," he says.

Wilmot says that this smaller tubing can produce the same vacuum effect as the pumps, in some cases, doubling production.

"I really feel like there is no question that this is a better way to create a gravity tubing system for the people that aren't using pumps," he says.

And who doesn't like the thought of more golden syrup being produced? Wilmot likes his syrup at breakfast.

"In my hot cereal every morning," he says.

So far the smaller tubing has been primarily used by producers who don't use pumps.

However, Wilmot says that some large maple producers are beginning to integrate the smaller tubing with their pumps to boost their vacuum even higher.